Method for maintaining level of drilling fluid



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METHOD FOR MAINTAINING LEVEL OF' DRILLING FLUID Original Filed April 10,1953 MUD LEVEL 9 BLOW-QUT 27 PRL-VENTO l I6 26 25 I 'Q zo 24-^ g l 25 Iaww-our me VEN T01? 22 L" PRESSURE OPERATED 36 "6 sw/rcH 36* 30v lINVENTOR. F 6 2, Wa/er J. Bie/stein,

United States Patent METHOD FOR MAINTAINING LEVEL F DRILLING FLUIDWalter J. Bielstein, Corpus Christi, Tex., assigner, by mesneassignments, to Esso Research and Engineering Company, Elizabeth, N. J.,a corporation of Delaware Original application April 10, 1953,- SerialNo. 348,026. Divided and this application June 3, 1954, Serial No.434,186

4 Claims. (Cl. Z55-1.8)

The present invention is directed to a method and apparatus fordetermining the status of drilling fluid. More particularly, theinvention is directed to a method and apparatus for determining theposition and flow of drilling mud in the drilling of wells. In its morespecific aspects, the invention is directed to a method and apparatusfor warning ldrillers of the condition of a well in drilling operations.

This application is a division of U. S. Serial No. 348,026, nowabandoned, entitled Method and Apparatus for Determining Status ofDrilling Fluid, filed April 10, 1953, for Walter l. Bielstein.

The present invention may lbe briey described as a method for use indrilling wells in which drilling fluid such as water, an aqueoussuspension of solids or an oil base mud, and the like, is circulateddown a hollow drill stem and upward through an annulus between the drillstem and the wall of the well, the particular feature of the inventioninvolving the steps of establishing a column of drilling lluid in theannulus and then establishing a column of air fluidly communicating withthe column of drilling fluid. The top or level of the mud in the annulusvaries depending on the operation being performed or the condition ofthe well. The column of fluid is balanced against a stream or column ofair under pressure and the changes in the fluid level in respect to thecolumn of air are measured by changes in the pressure required tobalance the two columns of unequal densities. The change in thebalancing pressure may be a result of several things among which will beremoval of drill pipe from the bore hole without adding fluid, loss ofreturns of the drilling uid, changes in the density of the drillingHuid, changes in circulation rate, etc. Changes in the air pressurerequired to balance the column of drilling fluid will be noted by theoperating pressure, and if such changes are not normal to the operationor conditions of the hole, then measures may be taken immediately tocorrect the condition.

Thus, the present invention contemplates establishing a column ofdrilling fluid and a column of air in Huid com munication with eachother at the lower end of the column of air and further establishingequilibrium conditions between the two columns. As the column ofdrilling fluid tends to lose drilling uid and equilibrium tends to bedisturbed or lost, my invention allows restoration of equilibrium byadding drilling lluid to the column of drilling fluid as the equilibriumbecomes disturbed.

The invention also involves apparatus for determining ow of drilling uidfrom the well which comprises, in combination, a bell nipple having aninlet and at least an outlet whose longitudinal axis defines a nearright angle with the longitudinal axis of the inlet. The bell nipple hasa ball bearing journalled in a wall thereof to which is rigidly attachedan actuator member which protrudes into a path of flow from the' inletof the bell nipple to said outlet thereof. A switch member is connectedto the ball bearing at a point opposite to the actuator member, theswitch member having a free end provided with a first l ice electricalcontact means. A housing is mounted on the wall of said bell nippleenclosing the switch member and a second electrical contact means ismounted in the housing and is arranged in operative relationship withthe rst electrical contact means to complete an electrical circuit. Abiasing means, such as a coil spring, is connected to the free end ofthe switch member and to the interior wall of the housing to urgenormally the switch means and said first electrical contact means awayfrom contact with the second electrical contact means. A warning meansis electrically connected to the rst and second electrical contact meansto provide an alarm on movement of the actuator member by movement ofthe drilling fluid along the path of ow.

The invention will be further illustrated by reference to the drawing inwhich Fig. l shows an arrangement of one type of apparatus forindicating the status of the drilling fluid in the drilling of a well;

Fig. 2 shows an arrangement for indicating the status of drilling uid ina well and the ow of drilling fluid from the well;

Fig. 3 is a sectional view of the bell nipple and its allied parts ofthe apparatus of Fig. 2; and

Fig. 4 is a. view taken at right angles to and showing a portion of thedevice of Figs. l, 2 and 3.

Referring now to the drawing, numeral 11 indicates the top joint of acasing in a well bore 15 which is connected by a collar 12 to the secondjoint of the casing 13, both of which may be retained by cement 14 inthe well bore 15. Connected to top joint 11 in the casing string nearthe surface is a small tubing 16 which is lead down from the earthssurface 17 down through the annulus between the casing string and thewell bore 15. The tubing 16 should Ibe constructed preferably of metalcapable of withstanding pressures equal to the test pressure of the topjoint 11 and suitably may be a steel or copper tubing or the like whichmay be readily attached by welds 18 to the top joint 11, as shown. Thetubing 16 may also be provided with valves 19 and 20 for the purpose ofblanking ofrr the lower portion of tubing 16 from the indicatingapparatus. The tubing 16 leads to the drillers position, as will bedescribed in more detail hereinafter. Connected to the top joint 11 bysuitable connection means 21 are standard blow-out assemblies and thelike which may consist of one or more blow-out assemblies. Forillustrative purposes, a two blow-out assembly is shown. Thus a bottomblow-out assembly or preventer 22 is connected to connection means 21and to llange 23. Connected to ange 23 is a spool or connecting means 24which may be provided with a tubing 25 which may lead to a chokemanifold and may be employed for controlling pressures that may developin the annulus between the hollow drill stem or string and the casingstring. The spool 24 is coni nected by flange 26 to a top blow-outpreventer 27.

Connected to the top blow-out preventer or top of a single or pluralityof blow-out preventer assemblies is a large diameter line 29 whichdescribes approximately a right angle to the vertical wellhead assemblyfor the purpose of directing the returning drilling lluid in the annulusto the mud pits. For purposes of illustration, this line 29 is commonlycalled a bell nipple having an inlet 30 and an outlet 31. The bellnipple is connected to ythe top blow-out preventer 27 by flange 28. Thebell nipple 29 has a second outlet 29 through which the hollow drillstem or string, not shown, is inserted for con ducting the drillingoperations. The outlet 31 communicates with the mud pit. Arranged in thebell nipple 29 in a path of llow from the 4inlet 30 to the outlet 31 isan actuator member 32 connected to a ball bearing 33 provided with aswitch member 34. The switch member i 34 is enclosed in -a housing 35.The switch member 34 is connected by electrical leads 36 to the drillersposition as will be described in more detail hereinafter. A drill stem10, shown in dotted lines to which a drilling bit not shown isconnected, is arranged in the casing 11 and extends upwardly through theblowout preventers 22, 27 and through the bell nipple 29 to the derrickoor, not shown. Mud is circulated down the drill stem to form a mudlevel, such as 9, which discharges through the outlet 31 of line 29. Theair introduced through line 16 bubbles upwardly Ithrough the mud, suchas shown by bubbles 8, and is discharged at the mud level 9.

In Fig. 2 the mud level 9 has dropped below the outlet 31 and below theelement 32 resulting from a disturbance in initial equilibriumconditions. It is to be noted in Fig. 1 the drill stem is shown in thewell, whereas in Figs. 2 and 3, the drill stem is not in the well.

Referring now to Fig. 2, identical numerals are employed to designateidentical parts, it will be seen that the steel or copper tubing 16 isprovided with an inlet 40 leading to a source of compressed air, notshown, and further is provided with a control valve 41. Connected to thetubing 16 is a conduit 42 to which is connected by tubing 43 a pressuregauge 44 which may be of the Bourdon tube type. Also connected to theconduit 42 by a conduit 45 is a pressure switch, of the conventionaltype, 46 which serves to energize a warning device 47 electricallyconnected thereto by electrical lead 48. The warning device 47 may be asuitable light or signal means. Electrically connected to the lead 48 isan electrical connection 49 leading to an audible warning device 50which suitably may be a bell, whistle, or the like, energized byelectrical energy. The visual warning device 47 and the audible warningdevice 50 both receive electrical energy from the battery 51 throughsuitable electrical connections 52 and 53. `It is understood, of course,that a suitable source of E. M. F., other than battery 51, may besubstituted therefor.

It will be noted with respect to Fig. 2 that the housing 35 is providedwith a second electrical contacting means 37 and a biasing means, suchas a coil spring 38, which normally urges the switch member 34 and itselectrical contact means 39 out of contact with electrical contact 37.

Referring now to Fig. 3 which is a single View of a portion of theapparatus of Figs. l and 2, apart from the remainder of the apparatus,it will be seen that the ball bearing 33 is journalled in the wallmember 60 of the bell nipple 29 and the actuator member 32 protrudes ina path of ow from the inlet 30 to the outlet 31. Also it will be seenthat the switch member 34 is attached to the ball bearing 33 at a pointopposite to the actuator member 32. The housing 35 serves to enclose theswitch member 34, the spring 38 and the second electrical contact means37. It will be noted that the electrical leads 36 are shown in moredetail in Fig. 3. The housing 35 is provided with a drain port 35a fordrainage of any moisture or iluid which may collect therein. It iscontemplated that the ball bearing 33 journalled in the wall 60 will besuitably sealed from ingress of drilling fluid from the path of ow tothe interior of the housing 35.

The apparatus of the present invention operates in the following manner:

During the drilling operations, it -is desirable to maintain a level ofdrilling mud in the top joint of the casing to permit visual inspectionof the status of the drilling mud; however, human frailty being what itis, it is not uncommon for drillers not to notice the condition of thedrilling mud or liuid. In my invention, a warning is sounded when thedrilling mud level falls below a certain point. In addition, anindicated pressure is available at all times from which to predict andanticipate changes in mud level. I connect into the topljoint of thecasing at a point varying from 25 to 75 feet below the earths surface asteel tubing through which air is introduced at a fixed minute rate andat a pressure suticient to overcome the column of mud above the pointwhere the tubing 16 connects to the casing 11. This air pressure will beslightly higher than that required to balance the head of uid from theopening in the casing to the height of the ow line. Just higher than thebalancing pressure, the minute amount of air entering the tube willbubble through the opening of the tube 16 at the point 16a into the topjoint 11, and the slightly higher than balancing pressure will beindicated at the drillers position P which will show the height of themud column -above the small opening 16a in the casing 11. Apressure-operated switch, such as 46, will energize a light, such as 47,which will remain on until the drilling iluid within the casing 11 dropsto the approximate height of the opening 16a. At this point, the airpressure will approach zero pounds per square inch and allowpressure-operated switch 46 to open and the signal light to go out,indicating to the driller that mud should be added to restore the columnof mud and air to original equilibrium conditions.

In the device -of Fig. 3 also shown in Figs. l and 2, the actuatormember 32 becomes operative when the liow of fluid passes the member 32causing the contacts 39 and 37 to complete the circuit. This causes asecond light 70 to be energized which shows the driller at the positionP that uid is being circulated. Also the audible signalling means 61 canbe caused to sound. This audible signalling means may be anelectrically-operated horn or a bell and the like. The light or theaudible signalling means will remain on when duid is circulating bymember 32. When no fluid is passing 32, such as when pumps are stoppedand no fluid is being circulated, or when the pumps are operating andreturn of the fluid to the surfaces has ceased because of going into theformation, the light will be olf. During periods when uid is not beingcirculated and the light fails to go out, it will indicate that the wellis flowing for some reason that should be investigated.

The device of the present invention has many advantages and much utilityin that it alarms the drilling crew when mud has fallen in the hole apredetermined amount when pulling the pipe from the hole. It also alarmsthe drilling crew when returns are lost. During periods when mud flowsback during operations which normally require the well to be shut down,the crew is alerted by means of my method and device. Also the presentinvention informs and alarms the drilling crew when a material change indrilling mud weight occurs.

The present invention also provides positive limits for measuring theamount of fluid required during trips into and out of the hole and givesa positive measurment of the amount of mud which has dropped as the pipeis pulled from the hole. By having these positive measurements, it ispossible to measure accurately when and if a well is attempting to flow.

During drilling operations if the returns light, such as 70, goes outand the pressure drops on the gauge 44, it is indicative of returnsbeing lost or only partial returns being obtained. In operations such asgoing into the hole if the returns light does not light up while runningeach stand of pipe in the hole, it is possible that mud returns havebeen lost. If the returns light fails to go out after the pipe slips areset, it is indicative that the well may be attempting to ow.

The nature and objects of the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Patent is:

1. In the drilling of a well wherein drilling fluid is circulatedthrough the bore during drilling thereof and wherein the level of thecolumn of drilling fluid is normally maintained at a predeterminedlevel, the improvement therein comprising the steps of injecting astream of air into the column of drilling iiuid under a pressure whichis equal to the pressure of the column of drilling uid to provideequilibrium between the stream of air and the column of drilling uid,and varying the supply of drilling fluid as the state of equilibriumbetween the stream of air and the column of drilling fluid is unbalanceddue to disruption thereof by reason 4of any change in the pressure ofthe column of drilling Huid.

2. In the drilling of a well wherein drilling fluid is circulatedthrough the bore during the drilling thereof and wherein the level ofthe column of drilling fluid s normally maintained at a predeterminedlevel, the improvement therein comprising the steps of injecting astream of air into the column of drilling fluid under a pressure whichis equal to the pressure of the column of drilling fluid to provideequilibrium between the stream of air and the column of drilling fluid,and increasing the supply of drilling fluid as the state of equilibriumbetween the stream of air and the column of drilling duid 6 isunbalanced due to disruption thereof by reason otl any decrease in thepressure of the column of drilling fluid.

3. A method in accordance with claim 2 in which the drilling fluid ismud.

4. A method in accordance with claim 2 in which the drilling fluid is anoil base mud.

References Cited in the le of this patent UNITED STATES PATENTS1,566,338 ,Mayhew Dec. 22, 1925 1,977,969 McIntosh Oct. 23, 19342,283,477 Walker May 19, 1942 2,340,993 Smith Feb. 8, 1944 2,360,742Toth et al Oct. 17, 1944 2,615,442 Berry Oct. 28, 1952

1. IN THE DRILLING OF A WELL WHEREIN DRILLING FLUID IS CIRCULATEDTHROUGH THE BORE DURING DRILLING THEREOF AND WHEREIN THE LEVEL OF THECOLUMN OF DRILLING FLUID IS NORMALLY MAINTAINED AT A PREDETERMINEDLEVEL, THE IMPROVEMENT THEREIN COMPRISING THE STEPS OF INJECTING ASTREAM OF AIR INTO THE COLUMN OF DRILLING FLUID UNDER A PRESSURE WHICHIS EQUAL TO THE PRESSURE OF THE COLUMN OF DRILLING FLUID TO PROVIDEEQUILIBRIUM BETWEEN THE STREAM OF AIR AND THE